The present invention relates to a drilling tool incorporating first and second ends, a cuttable and/or processable shaft extending between the ends. The first end has a drill bit to penetrate rock. The drill bit and the shaft have complementary threads. The drill bit and the shaft comprise a relative rotation stop means that ensures that the drill bit remains loose during drilling in a first direction. The invention further relates to a self drilling rock bolt, a drill bit, drill shaft and shaft coupling, and an anchoring device per se.
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1. A shaft of a drilling tool extending between opposing ends, one of the ends being associated with a drill bit to penetrate rock, the other end being associated with a drilling apparatus to allow rotation of the shaft, the shaft comprising:
a shaft section fabricated from glass reinforced polymer;
a connector piece fabricated from a metal; and
a mechanical joint joining the connector piece to the shaft section,
wherein the shaft section has opposing shaft section ends, the shaft section being arranged to be cut and/or processed by a mining machine,
wherein the connector piece is mechanically attached adjacent one of the shaft section ends, the connector piece being arranged to connect one of the drill bit, the drilling apparatus or an anchoring device to the shaft section, and
wherein the mechanical joint is a deformable member swaged, crimped and/or pressed around both the connector piece and the shaft section to secure the connector piece to the shaft section.
3. The shaft defined by
4. The shaft defined by
5. The shaft defined by
6. The shaft defined by
9. The shaft defined by
10. The shaft defined by
13. A self drilling rock bolt comprising:
the shaft defined by
an anchoring device extending along a first part of the shaft adjacent one of the ends.
14. The self drilling rock bolt defined by
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This application is the National Stage of International Application No. PCT/SE2009/050434, filed Apr. 24, 2009, and claims benefit of AU Application No.'s 2008904475, filed Jun. 25, 2008 and 2008230002, filed Oct. 17, 2008.
The present invention relates to drilling tools and rock bolts suitable for use in the mining and tunnelling industry to provide roof and wall support. The invention is suitable for use in hard rock applications as well as in softer strata, such as that often found in coal mines, and it is to be appreciated that the term “rock” as used in the specification is to be given a broad meaning to cover both these applications.
Roof and wall support is vital in mining and tunnelling operations. Mine and tunnel walls and roofs consist of rock strata, which must be reinforced to prevent the possibility of collapse. Rock bolts are widely used for consolidating the rock strata.
In conventional strata support systems, a hole is drilled into the rock by a drill rod, which is then removed and a rock bolt is then installed in the drilled hole and secured in place typically using a resin or cement based grout.
To improve this process, self drilling rock bolts have been proposed whereby the bolt is also used as the drill rod. As such, with a self drilling rock bolt, the hole can be drilled and the bolt installed in a single pass.
Whilst self drilling rock bolts provide the opportunity to substantially improve installation times of rock bolts, they have not been widely used, especially if the strata they are installed in subsequently requires processing.
In accordance with a first aspect of the present invention, there is provided a shaft of a drilling tool extending between opposing ends, one of the ends being associated with a drill bit to penetrate rock, the other end being associated with a drilling apparatus to allow rotation of the shaft, the shaft comprising:
a shaft section having opposing shaft section ends, the shaft section being arranged to be cut and/or processed by a mining machine; and
a connector piece attached adjacent one of the shaft section ends, the connector piece being arranged to connect one of the drill bit, the drilling apparatus or an anchoring device to the shaft section.
Some embodiments provide the advantage that a mine can be developed, especially at a long-wall mining site, using cuttable drilling tools or rock bolts that are left in the strata, and then the strata containing the tool/bolt can be cut away and/or processed by a mining machine without damaging or jamming the machine.
The use of a composite shaft as described above allows different parts of the shaft to have different properties. For example, the ends of the shaft or connectors may be formed of a machinable and strong material suitable for a coupler, but the shaft section may be formed of an easily cuttable material.
In an embodiment, the shaft section comprises a glass reinforced polymer portion.
Glass reinforced polymer is often advantageous to use because it is easily cut by the tools on the mining machine, and relatively easily broken during processing of the mined material including the cut tool/bolt. It is however, very strong in tension and thus suitable for this application.
In an embodiment, the connector piece comprises metal and is secured to the shaft section by a deformable member swaged, crimped and/or pressed around both the connector piece and the shaft section. The deformable member may extend further along the shaft section than the connector piece.
In an embodiment, the connector piece comprises a deformable member swaged, crimped, and/or pressed around the shaft section for securement of the connector piece to the shaft section. The connector piece may comprise metal. The shaft section may be shaped to provide a mechanical interference between the shaft section and the deformable member. The deformable member may be integrally formed with the connector piece.
The use of a deformable member in a crimp type connection is advantageous because it allows a shaft comprising dissimilar materials to be formed.
In an embodiment, the connector piece is fitted and/or moulded over a portion of the shaft section. The connector piece may be a polymer. The portion of the shaft section may be shaped to provide a mechanical interference between the shaft section and the connector piece. The connector piece may have an external thread. The external thread may be a rope thread.
An over-molded connector is often advantageous because it allows rapid and relatively cheap production. It also allows a wide variety of connector shapes and configurations.
In an embodiment, the shaft section comprises a conduit running along the length of the shaft section, the conduit opening out at ends of the shaft section.
According to a third aspect of the invention there is provided a connector piece having opposing ends, one end being arranged to be attached adjacent to an end of a shaft of a drilling tool, the other end being arranged to connect to one of a drill bit, a drilling apparatus to allow rotation of the shaft, or an anchoring device.
In an embodiment, the connector piece comprises a deformable member arranged to be swaged, crimped, and/or pressed around the shaft section for securement of the connection piece to the shaft section. Alternatively, the connector piece includes a connector piece comprises a threaded surface arranged to engage a corresponding threaded surface of the shaft.
In accordance with a fourth aspect of the invention there is provided a drilling tool comprising a shaft according to the first aspect of the invention.
In an embodiment, the drilling tool is a self drilling rock bolt. The rock bolt may be arranged for bolting a coal face in a long-wall mining operation. The mining machine may comprise a shearer or power loader.
In accordance with a fourth aspect of the invention, there is provided a self drilling rock bolt comprising a shaft extending between opposing ends, the shaft comprising a shaft section located between the ends arranged to be cut and/or processed by a mining machine, and an anchoring device extending along a first part of the shaft adjacent one of the ends.
In an embodiment the anchoring device has an internal thread that cooperates with an external thread on a connector fitted and/or moulded over a portion of the shaft section, the first part of the shaft having a drill bit to penetrate rock during drilling in a first direction and a stop to limit the rotation of the anchoring device on the shaft to maintain the anchoring device in loose threaded connection on the shaft during drilling.
It is convenient to hereinafter describe embodiments of the present invention with reference to the accompanying drawings. The particularity of the drawings and the related description is to be understood as not superseding in generality of the preceding broad description of the invention.
In the drawings:
In use, the connector piece 202 of the self drilling rock bolt 10 is connected to a drilling and bolting apparatus (not shown) and acts as a drill rod to drill a hole 100 (see
The drilling end 11, connected to the shaft 13 by another connector piece 200, incorporates a drill bit 15 incorporating a drill tip 16 at an end thereof and an anchoring device 23 which in use is arranged to retain the bolt in a drilled hole. The anchoring device 23 extends along the first part of the bolt 10 and is used to retain the bolt 10 in the drilled hole so as to temporarily secure the rock bolt in place prior to the introduction of grout into the hole 100 to permanently fix the bolt 10 in place and/or to tension the bolt 10 so as to place the rock strata 500 in compression.
The connector pieces 200 and 202 are formed of a metal, such as steel, and are secured to the glass fibre reinforced plastic shaft section 204 by the ductile metal members 206 and 208 which are swaged, crimped and/or pressed around both the connector 200, 202 and the shaft section 204. Suitable ductile metals for members 206 and 208 include low carbon steels such as 1010. The member 206, 208 may extend further along the shaft section 13 than the connector pieces 202, 200. This is because the amount of pressure that can be applied to the glass reinforced polymer shaft section 13 is less than the amount of pressure that can be applied to the steel connectors 200, 202 and thus a larger contact surface is required between the polymer shaft section 204 and the connectors 200, 202.
The details of the drilling end 11 are best seen in
During a drilling operation, the drilling apparatus typically induces right hand rotation to the drill shaft. To ensure that the drill bit 15 does not separate from the shaft during the drilling operation, the threaded coupling between the drill bit 15 and the shaft 13 is a right handed thread so as to tend to cause the threaded coupling between the drill bit and shaft to tighten during a drilling operation.
The drill bit 15 includes a bit body 17 which includes the drill tip 16 at its outer end and a drill bit shank 18 which incorporates a fastening means such as an external thread 22 on its outer surface. A passage 19 extends from the distal tip of the shank 18 through to the distal end of the bit body 17. This passage 19 is arranged to be in fluid communication with end port 61 of the inner passage 14 of the shaft when the drill bit 15 is secured to the shaft end 20 (as best seen in
The drill bit 15 is provided with a lower end surface 80 in connection with the drill bit shank 18. The end surface 80 extends substantially perpendicularly to the drill bit shank. The shoulder surface faces towards the shaft 13 when the drill bit has been mounted. The shoulder surface comprises at least one recessed surface 81 that incorporates an upstanding wall 82. The recessed surface 81 is in the illustrated form generally parallel to the lower surface 80 but in another form may be inclined at an acute angle α (shown in
The anchoring device 23 is disposed below the drill bit 15 and includes a pair of expansion elements 24 which are designed to be caused to move outwardly from a retracted position as illustrated in the drawings to an expanded condition (not shown) wherein the expansion elements 24 engage the wall 101 of the drilled hole 100.
The expansion elements 24 are interconnected by a connector or a bail strap 25. This connector is typically made from steel and includes a substantially circular body section 26 and connecting legs 27. The connecting legs 27 are riveted (or otherwise fixed) to a proximal end 28 of the expansion elements 24. The expansion elements are joined to the connector to form an anchor assembly. By making the connector 25 from steel, it can flex thereby providing a live hinge that allows pivoting of the expansion elements so as to enable them to easily move between their retracted and their extended position.
The body section 26 is preferably substantially circular and comprises a central hole 84 to receive the drill bit shank 18. The body section 26 is provided with at least one projection or upstanding tongue 83 at the surface facing towards the drill bit 15. The tongue 83 is preferably punched out of the body section at a mid-area location, i.e. at a location in between the hole 84 and a periphery of the body section. The tongue 83 has a general V-shape as best seen in
If the anchoring device is prone to get stuck at the shaft end 20, each leg 27 may carry a second stop or leading tag 42A, 42B, i.e. ‘leading’ if the connector 25 is rotated in the left hand direction. The tag 42A, 42B is provided adjacent to an end of the leg distal from the body section 26 and is integrated with the connector. In
The anchoring device 23 further includes a mandrel 29 which includes opposite inclined surfaces 30 and 31. In the illustrated form, the mandrel 29 includes a head portion 32 and two depending legs 33 and 34 with opposite faces of the head portion 32 and opposite edge surfaces of the legs 33 and 34 forming respective ones of the inclined surfaces 30 and 31. The head portion 32 may have two opposed grooves to house parts of the legs of the connector.
The mandrel is arranged so that the inclined surfaces 30 and 31 are generally flat and designed to abut with inner surfaces 35 of the expansion elements 24 in a manner such that relative movement of the mandrel towards the nut end 12 of the shaft causes the expansion elements to move from their retracted position to their extended position.
To enable this relative movement, the mandrel is coupled to the bolt shaft which in the illustrated arrangement is through a threaded coupling with an internal thread 36 formed in an inner bore 37 in the head portion 32 of the mandrel 29 and an external thread 38 formed on the bolt shaft 13.
The threaded coupling between the mandrel 29 and the bolt shaft 13 is a left handed thread so that when the rock bolt is undergoing a drilling operation (under right hand rotation of the shaft), any relative motion between the mandrel and the shaft would cause the mandrel to move towards the drill end thereby ensuring that the expansion elements are not moved to their expanded condition. However if there is too much movement, the mandrel would force the connector hard against drill bit so that the mandrel could not rotate under left hand rotation thereby preventing activation of the anchor as the mandrel could not wind down the shaft.
To prevent this occurring, the stop is provided by the cooperating abutment surfaces of the upstanding wall 81 and the tongue 83. This stop is active when these two surfaces move into engagement and limits the anchoring device from rotating on the shaft so as to maintain a space between an end surface of the anchoring device and an end surface of the drill bit during drilling.
The operation of the stop is best illustrated in
When the bolt 10 undergoes left hand rotation there is no impediment to the mandrel winding down the shaft as the two abutting surfaces of the stop do not prevent movement of the mandrel in that direction.
The anchoring device 23 may further comprise an annular band, not shown, which can be disposed around a distal end of the expansion elements 24. The annular band is typically made from a polymeric or rubber material and is provided to hold the expansion elements 24 together only during transport and start of drilling.
The tags 42A, 42B of the connector are arranged to adopt two conditions. In the first condition as illustrated in
Thus, the connector 25 performs several functions. The first function is to hold the expansion elements a set distance axially from the end of the shaft. The second function is to rotationally join the mandrel and the expansion elements together. The third function is to provide a hole so that the drill bit can be threaded into the shaft. The fourth function is to form part of a rotation stop that stops the mandrel from being screwed tightly against the drill bit. The fifth function is to provide tags that grip the bore wall during anchoring, thus allowing the anchoring device to rotate relative to the shaft.
Another variation of the rock bolt 10 is illustrated in
In the bolt 50, an expansion assembly 51 is provided that includes the expansion elements 24 and a collar 52 disposed about the shaft 13 of the bolt 50. The collar 52 functions in the same way as the connector 25 of the earlier embodiment and interconnects the proximal ends 28 of the expansion elements 24.
In contrast to the earlier embodiment, the expansion assembly 51 is orientated so that the distal ends 40 of the expansion elements face towards the drill end 11, rather than the nut end 12 as in the earlier embodiment. To prevent movement of the expansion assembly 51 towards the nut end 12, the assembly 51 is seated on a retaining device 53 that comprises a thrust ring 54 that is axially fixed to the bolt shaft 13 and a slip ring 55 disposed between the thrust ring 54 and the collar 52.
In an arrangement consistent with the earlier embodiment, the assembly 51 incorporates the mandrel 29 arranged so that its inclined surfaces 30 and 31 are designed to abut with inner surfaces 35 of the expansion elements 24. In this way relative rotation between the mandrel 29 and the expansion elements 24 about the shaft axis is inhibited. Further, relative movement of the mandrel 29 towards the nut end 12 of the shaft causes the expansion elements to move from their retracted position to their extended position. Furthermore, the mandrel is coupled to the bolt shaft by a threaded coupling (not shown). The threaded coupling between the mandrel 29 and the bolt shaft 13 is a left handed thread so that when the rock bolt is undergoing a drilling operation (under right hand rotation of the shaft), any relative motion between the mandrel and the shaft would cause the mandrel to move towards the drill end thereby ensuring that the expansion elements are not moved to their expanded condition. Under left hand rotation of the bolt 50 rotation of the expansion element is arranged to occur and whilst not shown, the anchor device 23 may also incorporate the band to promote this rotation. Because the mandrel portion 29 and the expansion assembly 51 rotate together, this rotation is translated to the mandrel 29, to activate the device 23 and cause movement of the mandrel towards the nut end 12.
In a similar manner to the earlier embodiment a stop is provided to prevent excessive movement of the mandrel towards the drill bit. However, in this embodiment the tongue 83 which forms one of the cooperating surfaces of the stop is formed directly on the mandrel 29.
As indicated above with reference to
Before operation, the anchoring device 23 is threaded onto the shaft 13 suitably until the shaft end 20 abuts against the lower side of the body section 26 of the connector 25. Then the drill bit 15 is threaded into the inner thread 21 of the shaft end until a drill bit shank end 86 engages a bottom 87 of the inner thread 21.
In operation, the bolt 10 is secured to a drilling apparatus, via the drive nut 43, which rotates the rock bolt in the first direction. Drilling fluid is pumped around the circulation path, that is, the inner passage 14, and outer passage 64 to flush the rock cutting surface of the rock bolt. The fluid is either introduced or withdrawn from a port in the irrigated drive nut 43.
On completion of the drilling phase, the drilling apparatus then rotates the bolt in the opposite direction. The drive nut 43 rotates with the shaft 13 as relative movement is prevented by a torque pin. This causes the tags 42 (if present) to flare outwards causing the connector to grip the wall surface 101 causing the expansion elements 24 and mandrel 29 to start to slip relative to the bolt shaft. This relative movement induced between the anchoring device and the shaft causes the mandrel to wind down the thread of the shaft thereby causing the expansion elements to displace radially outwardly to engage the rock surface of the drilled hole.
When the expansion elements are engaged with the wall surface, the bolt is placed in tension by continuing to apply torque in the second direction to the drive nut 43. At a particular point, the expansion elements 24 are forced so hard against the rock wall surface that the mandrel cannot move down the shaft any further. This then effectively binds the bolt and inhibits it from rotating any further. This builds up the torque at the drive nut 43 until it reaches a point where it will shear a torque pin thereby letting the drive nut to move relative to the shaft. This relative movement then causes the nut to wind up the shaft.
Once the drive nut is able to move along the bolt shaft, it will then move into engagement the outer face of the rock strata 500 (either directly or through the bearer plate) which will then enable the bolt to be placed in tension as the effective length of the bolt between the drive nut and the anchoring device is shortened. Once the bolt is under sufficient tension, the drilling apparatus can then be removed and possibly for further support a final stage of setting the bolt in place by the introduction of the grout through a port in the drive nut 43 can take place.
In yet another alternative embodiment, as illustrated in
One of the drill bit and the shaft is provided with a projection 83′ and the other with a recess 81′. The projection and an upstanding wall 82′ of the recess 81′ abut to stop relative rotation of the drill bit and the shaft. The threads 21′ and 22′ are matched such that the projection 83′ will enter into the recess 81′ to provide a minimum gap between the shoulder surface 80′ of the drill bit and the end of the shaft 13′. The projection and the recess have been described more closely above in connection with the previous embodiment.
An alternative shaft 90 to the shaft 13′ for the drilling tool of
However in contrast to the shaft 13′ which is made as an integral element, the shaft 90 includes a major portion 94 and an end portion 95. These portions 94 and 95 are axially aligned with the end portion 95 incorporating the threaded coupling 93 to receive the drill bit and the projection 91 on its distal end.
In the illustrated form, the main portion 94 is a conventional drill rod and includes a drive element 98 formed adjacent the second end 99 which is arranged to be connected a drilling apparatus to provide rotation and thrust to the drilling tool. The end portion 95 is in the form of an end coupling incorporates a threaded shank 97 (as best seen in
In the claims which follow and in the preceding description of relative rotation stop means where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
It will be appreciated that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
Horsch, John, Knight, Simon Daniel Hardwicke
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Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
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Nov 15 2010 | KNIGHT, SIMON DANIEL HARDWICKE | Sandvik Intellectual Property AB | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 025610 | /0093 | |
Nov 16 2010 | HORSCH, JOHN | Sandvik Intellectual Property AB | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 025610 | /0093 |
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